BioSc 321
General Genetics
Exam 2
Name __________________________________
Multiple Choice. (1 point each)
_____During anaphase of the mitosis ___.
A. DNA recombines
B. Sister chromatids move to opposite poles
C. The nuclear membrane disappears
D. RNA replicates
E. DNA content essentially doubles
_____During prophase of mitosis ___.
A. DNA recombines
B. Sister chromatids move to opposite poles
C. The nuclear membrane disappears
D. RNA replicates
E. DNA content essentially doubles
_____An autosome is ___.
A. a non-sex determining chromosome
B. an alternate form of a gene
C. another term for epistasis
D. present only in males and is responsible for sex determination
E. found in mitochondria but not in nuclei
_____What ratios typically result from crosses dealing with a single genetic locus?
A. 9:3:3:1, 1:2:1
B.1:1:1:1, 1:4:6:4:1
C. 3:1, 1:1, 1:2:1
D.9:7, 12:3:1
E. 15:1, 1:2
_____With co-dominance, a likely ratio resulting from a monohybrid cross would be ___.
A. 3:3
B. 1:2:2:4
C. 1:2:1
D. 9:3:3:1
E. 3:1
_____A situation in which an organism has both haploid and diploid stages would be called ___.
A. multiple alleles
B. alternation of generations
C. codominance
D. incomplete dominance
E. hemizygosity
_____ An F2 generation in which the phenoypic ratio of the offspring is 9:7 is usually due to ___.
A. codominance
B. epistasis
C. dominance
D. recessiveness
E. additive alleles
____ In a complementation test the number of complementation groups indicates
A. the number of genes required for a specific phenotype
B. the penetrance of phenotype
C. the number of alleles for a gene
D. the number of chromosomes in an organism
E. the quantity of gene product required for a phenotype
_____Typical phenotypic ratios resulting from epistatic interactions in a monohybrid cross would be ___.
A. 9:3:3:1, 1:2:1
B. 1:1:1:1, 2:1
C. 9:3:4, 9:7
D. 3:1, 1:2:1
E. none of the above
_____Chromosomes that contain the same sets of genes and pair up in meiosis I are called ___?
A. homologous
B. heterologous
C. complementary
D. non-disjunctive
E. parallel
_____ In a complementation test
A. mutations that complement are allelic
B. mutations that complement belong to the same complementation group
C. mutations that complement are in two different genes required for the wild-type phenotype
D. mutations that are allelic are required for complementation
_____ The purpose for check points in the cell cycle is to
A. cause cells to grow out of control leading to cancers
B. stop mitosis to prevent chromosome duplication
C. stop DNA synthesis to prevent chromosome duplication
D. pause the cell cycle until all the necessary building blocks are synthesized
E. give geneticists something else to study
_____ Which stage of prophase I of meiosis is characterized by the initiation of active pairing?
A. leptotene
B. zygotene
C. pachytene
D. diplotene
E. diakinesis
_____ Which stage of prophase I of meiosis is characterized by the initiation of chromosomal “thickening”?
A. leptotene
B. zygotene
C. pachytene
D. diplotene
E. diakinesis
_____ Which stage of prophase I of meiosis is characterized by fully compacted chromosomes ready to begin metaphase?
A. leptotene
B. zygotene
C. pachytene
D. diplotene
E. diakinesis
_____ The percentage of individuals with a given genotype who exhibit the phenotype associated with that genotype is called
A. penetrance
B. expressivity
C. incomplete dominance
D. co-dominance
E. lethality
_____ A situation where each allele produces a protein that can be detected in the heterozygote is called
A. penetrance
B. expressivity
C. incomplete dominance
D. co-dominance
E. lethality
_____ A situation in which an allele causes inviability when present in two doses is called
A. penetrance
B. expressivity
C. incomplete dominance
D. co-dominance
E. lethality
_____ An allele that reverses the effect of a mutation of another gene, resulting in a wild-type phenotype is a(n)
A. activator
B. repressor
C. suppressor
D. dominator
_____ Which of the following is not true for histones?
A. They are rich in basic amino acids
B. They are associated with the nucleosome.
C. H1, H2, H3 and H4 form the nucleosome core.
D. They are found in the nucleus.
E. H1 functions as a monomer.
_____ Which of the following is not true about chromosome structure?
A. A telomere is always on the end of a eukaryotic chromosome.
B. A centromere is always in the middle of a eukaryotic chromosome
C. A chromatid is a chromosome that has been replicated but has not yet separated from its sister chromatid.
D. The kinetichore is the site of attachment of the centromere to the nuclear spindle apparatus.
E. Heterochromatin are primarily associated with the centromere and telomere regions.
_____ Mating type refers to
A. the number of sex-chromosomes in a eucharyotic cell.
B. a system in which haploid fungal cells only fuse with fungal cells with a different complement of alleles.
C. the gametes of a plant which undergoes alternation of generation.
D. the gametophytes of a flowering plant.
E. the sporophytes of a flowering plant.
_____ Which of the following processes occurs in meiosis but not mitosis?
A. Cell division
B. Separation of homologous centromeres to opposite poles
C. Chromatic formation.
D. Chromosome condensation (shortening)
E. Pairing of homologs.
_____ In swine, when a pure-breeding red is crossed with a pure-breeding white the F1 are all red. However, the F2 shows 9 red, 1
white and 6 of a new color, sandy. The Sandy phenotype is most likely determined by
A. complementary alleles of two different genes.
B. a heterozygote of the alleles determined red and white
C. recessive epistasis
D. the presence of a dominant allele at either of the two loci and red is determined by the dominant allele of both loci.
_____ A person who has type O blood has
A. A antigens on the cell surface
B. B antigens on the cell surface
C. both A and B antigens on the cell surface
D. no surface antigens
_____ The following coat colors are known to be determined by alleles at one locus in horses: Palomino = golden coat; Cremello =
almost white; Chestnut = brown. The following table gives the ratios obtained in matings of the above varieties:
Cremello x cremello – all cremello
Chestnut x chestnut – all chestnut
Cremello x chestnut – all palomino
Palomino x palomino – ¼ chestnut, ½ palomino, ¼ cremello
Based on these data, what are the genotypes of each type of horse?
A. AA = Chestnut; Aa = Cremello; aa = Palomino
B. AA = Cremello; Aa = Chestnut; aa = Palomino
C. AA = Palomino; Aa = Cremello; aa = Chestnut
D. AA = Palomino; Aa = Chestnut; aa = Cremello
E. AA = Chestnut; Aa =Palomino; aa = Cremello
_____ Homologous chromosomes are those which can be matched by virtue of their similar structure and function within a nucleus.
What chromosomes making up a genome do not follow the same characteristics of homology?
A. autosomes
B. sex-chromosomes
C. mating types
D. heterokaryons
_____ In Drosophila the recessive alleles for brown and scarlet eyes (resulting from two independent genes) interact so that the double
homozygous recessive is white. A pure-breeding brown and pure breeding scarlet are crossed. What proportion of the F2 will be white?
A. 1/4
B. 3/4
C. 1/16
D. 7/16
E. 9/16
_____ In chickens the dominant allele Cr produces the creeper phenotype (having short legs). However, the creeper allele is lethal in
the homozygous condition. If two creepers are mated, what proportion of the living progeny will be creepers?
A. 1/4
B. 1/2
C. 3/4
D. 1/3
E. 2/3
_____ In the purple penguin, a series of alleles occurs at the p locus on an autosome. All alleles affect the color of the feathers. pd =
dark-purple; pm = medium-purple; pl = light-purple; pvl = very pale-purple. The order of dominance is pd > pm > pl > pvl. If a lightpurple female (heterozygous for very pale-purple), is crossed to a dark-purple male (heterozygous for the medium-purple), the ratio of
phenotypes expected among the baby penguins would be:
A. 2dark: 1 medium: 1 light
B. 1 dark: 1 medium
C. 1 dark: 1 medium: 1 light: 1 very pale
D. 1 medium: 1light
E. 2 dark: 1 light: 1 very pale
Matching. Match the type of repetitive DNA with the appropriate description.
Repetitive DNA
Description
_____ Dispersed gene family
A. Examples include immunoglobulin, actin, myosin genes
_____ Satellite DNA
B. “movable” DNA
_____ Variable number tandem repeat (VNTR)
C. Multiple dinucleotide repeats
_____ Transposon
D. Also known as minisatellite DNA, used for DNA fingerprinting
_____ Microsatellite DNA
E. Clustered primarily in heterochromatin
Problems (variable points each)
(4 points) An experiment to determine the inheritance of flower color in snap dragons crossed two plants with pink flowers. The
following progeny were recovered from the cross. 92 plants had red flowers, 210 had pink flowers and 98 had white flowers. How is
flower color inherited in snap-dragons? Indicate the predicted genotype for each flower color. Calculate the Chi-square value for the
data and use the chart below to determine if the data supports your analysis or not.
(4 points) Based on the complementation data below, A) how many complementation groups are represented in this table? B) which
mutations belong to each group? (+ = complementation, -- = no complementation)
1
2
3
4
5
6
7
1
-+
-+
+
+
--
mutation number
2 3 4 5
-+
-+
-+
-+
+
+
--
-+
-+
-+
+
6
7
-+
--
The figure below contains several figures that are supposed to represents chromosomes in anaphase of either meiosis or mitosis. The
organism represented is a diploid having 2n = 4 which includes one long pair and one short pair of metacentric chromosomes.
(2 points) Please cross out those that are not possible.
(1 point) Please indicate which diagram(s) properly represents chromosomes in meiosis I.
(1 point) Please indicate which diagram(s) properly represents chromosomes in meiosis II.
(1 point) Please indicate which diagram(s) properly represents chromosomes in mitosis.
(1 point) Please indicate which pair of diagram(s) properly illustrates independent assortment.
(1 point) Please indicate which pair of diagram(s) properly illustrates independent assortment.
(6 points) In a certain breed of dog, the alleles B and b determine black and brown coat respectively. However, the allele Q of a gene
on a separate chromosome is epistatic to the B and b color alleles (q has not effect on coat color). If animals of genotype B/b;Q/q are
intercrossed, what phenotypes do we expect to see in the progeny and indicate the expected ratio for each phenotype?
(4 points) In sweet peas the allele C is needed for color expression (c results in no color – white). The precise color expressed is
determined by the alleles R (red) and r (blue). A cross between certain red and blue plants result in progeny as follows:
3/8 red
3/8 blue
1/4 white
What are the genotypes of the plants crossed?
5 point bonus question Assume pigmentation in rabbits is controlled by 2 genes (E and H). Each gene exhibits complete dominance
and the relationship between genotype and phenotype are listed in the following table:
Genotype
E/-; H/h
Phenotype
Albino
e/e; H/h
Brown
E/-; h/h
Albino
E/e; h/h
Albino
Answer the following questions.
a) 2 brown parents produce an albino baby rabbit. What are the genotypes of the parents and the baby rabbit?
b) What phenotypic ratio would be expected among the progeny of an intercross between dihybrid rabbits.
c) In a litter of 5 baby rabbits from the cross in part b, what is the probability that all 5 of the babies will be albino? (If you do not
have a calculator it is OK to just set up the equation with the appropriate values)